The present invention relates generally to an electroplating apparatus for plating of semiconductor components, and more particularly to an electroplating apparatus, including a plating contact configured to make substantially continuous contact with an associated semiconductor workpiece, with the arrangement preferably including a peripheral seal member for sealing a peripheral region of the workpiece from electroplating solution during processing.
Production of semiconductor integrated circuits and other semiconductive devices from semiconductor wafers typically requires formation of multiple metal layers on the wafer to electrically interconnect the various devices of the integrated circuit. Electroplated metals typically include copper, nickel, gold and lead. Electroplating is effected by initial formation of a so-called seed layer on the wafer in the form of a very thin layer of metal, whereby the surface of the wafer is rendered electrically conductive. This electroconductivity permits subsequent formation of a so-called blanket layer of the desired metal by electroplating. Subsequent processing, such as chemical mechanical planarization, removes unwanted portions of the metal blanket layer formed during electroplating, resulting in the desired patterned metal layer in a semiconductor integrated circuit or micro-mechanism being formed.
Several technical problems are typically associated with electroplating of semiconductor wafers. Utilization of discrete electrical contacts with the seed layer of the wafer, about the wafer perimeter, ordinarily produces higher current densities near the contact points than at other portions of the wafer. This non-uniform distribution of current across the wafer, in turn, causes non-uniform deposition of plated metallic material. Current thieving, effected by the provision of electrically-conductive elements other than those which contact the seed layer, can be employed near the wafer contacts to minimize such non-uniformity, but such thieving techniques add to the complexity of electroplating equipment, and increase maintenance requirements.
Another typical problem in connection with electroplating of wafers concerns efforts to prevent the electric contacts themselves from being plated during the electroplating process. Any material plated to the electrical contacts must be removed to prevent changing contact performance. While it is possible to provide sealing mechanisms for discrete electrical contacts, such arrangements typically cover a significant area of the wafer surface, and can add complexity to the electrical contact design.
It is sometimes desirable to prevent electroplating on the exposed barrier layer near the edge of the semiconductor wafer. Electroplated material may not adhere well to the exposed barrier layer material, and is therefore prone to peeling off in subsequent wafer processing steps.
Finally, the specific metal to be electroplated can complicate the electroplating process. For example, electroplating of certain metals typically requires use of a seed layer having a relatively high electrical resistance. As a consequence, use of the typical plurality of electrical wafer contacts (for example, six (6) discrete contacts) may not provide adequate uniformity of the plated metal layer on the wafer.
The present invention is directed to an improved electroplating apparatus having a plating contact, and associated seal member, wherein the contact is configured to provide substantially continuous electrical contact with the associated wafer or like workpiece, with the seal member desirably providing continuous sealing of the peripheral region of the wafer from the electroplating solution.